hello pizzio,
since these are invoices, I am going to assume the invoice number is consistant with the placing of characters.
For OP
=MID(A1,SEARCH("OP",A1),2)
For first date
=DATE(20&MID(A1,16,2),MID(A1,15,1),1)
For last date
=DATE(20&RIGHT(A1,2),LEFT(RIGHT(A1,3)),1)
If the invoice is not consistant then you will need more complex formulas.
good luck